Saint Mary's beacon. [volume] (Leonard Town, Md.) 1867-1983, 1887-02-03

saIu 10 Constitute among then some
thing like an auihoritive reply. The
density of the earth Is foand to be
nearly as possible FIVE and half times
a great as that Of water, that Is, our
globe is equal in weight to FIVE and a
half globes of the same size composed
of water. But as the average or mean
density Of the rocks composing the
crust Of the earth ia only two aud a
half times greater than that of water,
it must follow that the layers Of ma
terial Of which the mass Of the earth's
unknown interior is composed must
be Of much greater density than the
rocks at the surface. Moreover, that
density may be supposed TO increase
by compression the nearer We APP
proach the centre. Were the inter-
nal materials of the same nature as
those at the surface. they would at the
depth OF few miles be SO compressed,
supposing such extent Of compression
possible, as to give much greater
mean density to the whole mass than
the ascertained facts will admit of.
For instance, it has been calculated
thai water at the depth of three hun
bred and sixty-two miles would be
as heavy as quicksilver. Now, this
metal at the surface of the earth is
fourteen times heavier than water;
therefore, water at the depth of three
hundred and sixIy-two miles wonld be
rendered by compression fourteen times
more dense than IL Is in its normal
condition. Following the same line
OF calculation, marble would AT the
centre Of the earth. be one hundred
and nineteen times more dense than
Il rs AT the surface Professor Judd.
however, IN hI> recent work on Vol
canoes, expresses the opinion that the
ascriblng of such almost unlimited
compressibility to solid substances can
be supported neither by experiment
nor bv analogy; as various consider
atoms point TO the probability that
solid bodies yield 10 pressure mp to
certain limit and no further. aud that
when this limit is reached all increase
in pressure is no longer attended with
a reduction in bulk.
1t was in view Of the difficulties
which attended this enormous com
preston Of the ordinary materials
found Al the earth surface, that phys
iclsts had recourse TO the theory that
the interior of the globe was mass
of molten matter surrounded by a
solid crust. This theory commended
itself to Fourier and Humboldt; and
after their time, had come TO be ac-
cepted almost as an ascertained truth.
Among other arguments advanced in
support Of the theory, was the fact, Of
which there cannot be any doubt, that
a high temperature exists in the
esrth's crust at some depth from the
surface. The borings that have been
made and the shafts sunk in Connec-
ton with mining operations, prove
that a more or less Regular increase Of
temperature takes place As We pene-
trats downwards, the average rate Of
increase being about one degree Fab
renheit for every fifty or sixty feet III
depth, although the rate Of Increase
varies very much as between different
localit .es. From the data thus ob-
talued, Professor Judd has calculated
that, supposing the heat to go or in
creasing III the above ratio, there vii!
be found, at a depth of nine thousand
feet, temperature Of two hundred
and twelve degrees Fahrenheit, sui
tlcIent to boil water at the earth :
surface; while at depth OF twenty
eight miles the temperature will be
high enough TO melt cast iron, and ~
thirty four m'iss TO fuse platinum.
SO marked" saws the last-paned
scientist, us this steady Increase of
temperature as We GO downwardS. that
1t has been seriously proposed to make
very deep borlngs in order TO Obtain
supplies Of warm water for heating our
towns. Arago and Walferdin SUI
/ gested THIS method for Warming the
Jardln DIES P,antes at Paris: aud aow
that such important improvements
have been devised ia Carrying horlngs
10 enormous depths. the time mas
not he far distant when We shall draw
extensively npon these supplies u sub
ierranean heat. At the present time,
the city of Buda Psslh Is extensively
supplied with no, water from AN IN
deIgrVund source. Should cur coal
supply ever tail, It may be Wal! to lie
member that We have these iuexhaus-
lbie supplies Of heat evsiywhe,e be-
meath our ieei.
But while the author We have lust
quoted admits the exl>tence Of this in.
creasing temperature within a limited
depth from The earth = surface. he vet
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